Self-powered flexible persistent displays for trajectory recognition

Self-powered display systems that integrate alternating current electroluminescence (ACEL) devices with triboelectric nanogenerators (TENGs) have shown great promise in human-machine interaction, smart displays, and security communications within the Internet of Things (IoT). However, their development has been significantly limited by undesirable flickering, which arises from the pulsed output characteristics of TENGs. Here, high-performance persistent phosphors ((Ca_0.25Sr_0.75)S:Eu) are incorporated into the ZnS:Cu-based ACEL devices to overcome this limitation, achieving an extended afterglow lifetime of 81 s and a sustained red emission lasting over 200 s. By integrating with TENGs, a self-powered persistent display system is realized that maintains bright red-emission for over 15 s. The varying afterglow intensities post power-off can distinguish directional movement (forward or backward), enabling motion trajectory recording and recognition, as demonstrated using floor-mounted TENGs to drive persistent display arrays. This strategy offers a new pathway for advanced self-powered display systems and broadens their application potential in the IoT landscape.